Re: Larger memory option for VAXstations

[Miod Vallat <miod%online.fr@localhost>]

> I don't have any hardware information, but an educated guess would be 
> that you need some additional address lines routed from the CPU to the 
> memory sockets. The CPU itself have the necessary address lines on pins, 
> but unless they also go to the memory sockets, you cannot get that high 
> in memory. But from a CPU point of view, there is nothing speical about 
> going to 512 Megs. Or even more. But if you go for more physical memory, 
> you need an NVAX (which I think the 4000 machines have), and the OS 
> needs to change the mode of the CPU, which I suspect VMS will not do on 
> a 4000 machine, as they would not expect you to have that amount of 
> physical memory that would require changing from the default mode.

I'm afraid the large physmem mode allowing more than 512MB of physmem is
only available on NVAX+ cpus (those pin-compatible with 21066), not
NVAX.